Well, after finding a dead battery in my truck after it sat for a week I noticed that the charging light was flickering and the battery did not charge after a long ride.... So i replaced the batter with a known good one and the light was gone.... the truck sat for another week and I jump in to find the battery being week and the charge/brake light staying on.

Figuring it was the brushes I pulled the alt, and put in brushes out of a good alternator only to find it still not charging, I put the brushes back in the other alt, install it and the truck charges fine, leading me to belive something else has gone wrong with the first alt.

Are there any tests I can do while the alt is off the truck to determine what is wrong with it and if it is worth fixing so I can have a spare alt again??

CLIF NOTES:

Alt went bad, replaced brushes, still not charging so I put in a different alt and the truck it fine. I still want to have a spare so I am wondering what I should look for and what I can do to bench test the alt as I am a little tired of taking the alt in and out to test it.


Thank guys,
Dustin

On these second gen trucks, the alternator has an IC unit which is integral to the alternator. The earlier trucks had an external voltage regulator, mounted near the coil.

Sounds like the IC went dead. I was able to do 4 brush swaps as the original owner of my truck before the diodes finally died.

Sounds like you are unaware that you can have the alternator tested FREE at a parts store like NAPA or Schmucks. Do that, instead of crawling under your rig to round-robin stuff.

As a consumer, 3 things you can ask them to check for you before you leave the parts store:
Battery--load/cell test
Alternator
Starters
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You might not have a spare alternator, but at least you'll have yourself a core return up front later on. Check it out.

good idea.... i'll have them test it

I have heard of the diods going bad in the alt as well.... is this a possibility?